Not sure if I should go to work tomorrow

I am in a dilemma. I hurt my back at the weekend on Saturday morning, picking up something very heavy. The pain was delayed and didn't have any problems until Sunday afternoon/evening. Anyway, could not sleep most of the night in agony with it. I took the day off work and went to the Doc's to get strong pain killers. As I know there is not much they can do with back pain. She said it was a muscle spasm and gave me Co-Dydramol. I still did not sleep properly on the Monday evening. Pain killers did not work even with Ibuprofen on top (up and down half the night). I went into work the following day, but didn't stay long as the pain was unbearable. I went back to the Doc's again yesterday and she prescribed me stronger Co-Dydramol and Valium dosed up all night, but still awake with the pain. I am due in again tomorrow, but not sure if I should go in still finding it hard walk properly. But you know what's its like you feel really guilty if you don't go in. Most of the job is sitting. What would you do. The Doctors say you should continue as normal. Am I being lazy?

Hello Wander, I was going to take the bus, but in such pain. When I went to the Doc's on Monday she said I should carry on as normal and go to work. It's crazy you feel so guilty. What back pain do you have?